Effect of dietary intake and lifestyle factors on in vivo mutant frequency at the HPRT gene locus in healthy human subjects

This paper describes the results of a study designed to assess the effects of a variety of dietary and lifestyle factors on background levels of mutant frequency (MF) at the hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene locus in humans. Eighty-three healthy and free-living subjects (aged 20–80 yr; 61 males and 22 females; mean age of 63.07±14.71 yr) were recruited. Background levels of MF were determined for each subject using a cloning assay. The mean MF/10⁶ clonable cells (MF) for the study subjects was 4.63±2.20. An interview-administered questionnaire was completed by each study subject in order to assess details of dietary history, physical activity, health and potential genotoxin exposure history. A 7-day estimated dietary record method with a food frequency questionnaire was used to determine average intakes of energy and macronutrients (including alcohol), and a range of micronutrients (including vitamin and mineral supplement usage). The relationships between individual dietary and lifestyle factors and HPRT MF were investigated by univariate and multivariate analysis (data was adjusted for age, lymphocyte plating efficiency PE] and energy intake EI]). Univariate analysis revealed a significant positive correlation between EI and MF and multivariate analysis revealed significant positive correlations between, body mass index (BMI), % energy intake from total carbohydrate, starch, fat and MF. These findings suggest that a reduction in EI may be a useful preventative measure against the onset of carcinogenesis in humans. No correlations were found between alcohol intake and MF or between estimated antioxidant intake and MF. Thus, estimated intakes of antioxidants may not reflect their bioavailability and functional capacity in vivo and it may be more useful to examine actual plasma/cell levels vs. MF to establish if any significant relationship exists.